1. Field of the Invention
This invention relates to an infection protectant useful for the prevention of infectious diseases caused by pathogenic bacteria or virus.
2. Description of the Prior Art
Antibiotics have heretofore been used for the treatment of infectious diseases caused by pathogenic bacteria. Although their effects are remarkable, their administration to allergic subjects may lead to death from shock and similar problems. In many instances, substantial limitations are therefore imposed upon their application.
It is generally practised to administer a vaccine against an infectious disease caused by virus. Since virus itself tends to undergo mutation or the like, it is not seldom that vaccination does not work well. Regarding influenza virus in particular, the type of virus which spreads changes every year and mass vaccination for schoolchildren and the like is considered to be almost meaningless.
There is hence a strong demand for the development of an infection protectant which gives no adverse effects to allergic subjects and does not lose its preventive effects by mutation of virus.
Incidentally, it has been reported that certain non-specific hemagglutination inhibition factors are contained in human milk and cow milk also have similar activities as the above factors although not so strong as human milk [Saito, et al., "Agricultural Biological Chemistry", 36. 1437-1439 (1972)]. It has hence been assumed that cow milk also contains one or more substances which undergo a direct interaction with the receptors of pathogenic bacteria or virus.
Oligosaccharides and ganglioside, which contain N-acetylneuraminic acid, have conventionally been known as such substances. They are believed to prevent infection by undergoing an interaction with the receptors of pathogenic bacterial or virus.
However, these substances have a small molecular weight. It is therefore essential to administer them in a substantial amount in order to allow them to undergo an interaction with all receptors for the exhibition of their effects. They are hence not practical.
Namely, no infection protectant having sufficient effects and safety has yet been realized.